U.S. patent application number 11/209052 was filed with the patent office on 2006-03-02 for catalyst for the synthesis of dimethyl carbonate from urea and methanol, preparation and use thereof.
Invention is credited to Yanjun Chen, Baoyuan Sun, Yuhan Sun, Wei Wei, Bingsheng Zhang, Ning Zhao.
Application Number | 20060047136 11/209052 |
Document ID | / |
Family ID | 34662842 |
Filed Date | 2006-03-02 |
United States Patent
Application |
20060047136 |
Kind Code |
A1 |
Sun; Yuhan ; et al. |
March 2, 2006 |
Catalyst for the synthesis of dimethyl carbonate from urea and
methanol, preparation and use thereof
Abstract
A catalyst for the preparation of dimethyl carbonate from urea
and methanol having a composition on weight base of: active
component of from 20 to 50 wt %, and carrier of from 80 to 50 wt %,
and prepared by equal-volume spraying and impregnating method is
disclosed. The method for the synthesis of dimethyl carbonate can
be carried out in a catalytic rectification reactor, said method
comprising: (1) dissolving urea in methanol to form a methanol
solution of urea; and (2) feeding the methanol solution of urea and
methanol counter-currently into the reaction zone, wherein the
reaction is carried out at conditions including reaction
temperature of from 120.degree. C. to 250.degree. C., reaction
pressure of from 0.1 MPa to 5 MPa, kettle bottom temperature of
from 70.degree. C. to 210.degree. C., stripping section temperature
of from 70.degree. C. to 250.degree. C., rectifying section
temperature of from 70.degree. C. to 280.degree. C., and reflux
ratio of from 1:1 to 20:1. The preparation of the catalyst
according to the present invention is simple and has good
repeatability, and the catalyst could further enhance the yield of
DMC as well as conversion of urea in the catalytic rectification
reactor.
Inventors: |
Sun; Yuhan; (Taiyuan City,
CN) ; Wei; Wei; (Taiyuan City, CN) ; Zhao;
Ning; (Taiyuan City, CN) ; Sun; Baoyuan;
(Shandong, CN) ; Zhang; Bingsheng; (Shandong,
CN) ; Chen; Yanjun; (Shandong, CN) |
Correspondence
Address: |
J. Michael Martinez de Andino, Esq.;HUNTON & WILLIAMS LLP
Riverfront Plaza, East Tower
951 E. Byrd Street
Richmond
VA
23219-4074
US
|
Family ID: |
34662842 |
Appl. No.: |
11/209052 |
Filed: |
August 22, 2005 |
Current U.S.
Class: |
558/277 |
Current CPC
Class: |
C07C 68/00 20130101;
B01J 23/02 20130101; B01J 23/06 20130101; B01J 23/10 20130101; B01J
23/14 20130101; B01J 23/34 20130101; Y02P 20/127 20151101; Y02P
20/10 20151101; C07C 68/00 20130101; C07C 69/96 20130101 |
Class at
Publication: |
558/277 |
International
Class: |
C07C 69/96 20060101
C07C069/96 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 27, 2004 |
CN |
2004100125041 |
Claims
1. A catalyst for the preparation of dimethyl carbonate from urea
and methanol, characterized in that the catalyst has a composition
on weight base of: active component: from 20 to 50 wt %, and
carrier: from 80 to 50 wt %, wherein the carrier is selected from
the group consisting of active carbon, .alpha.-alumina,
.gamma.-alumina, silica, and molecular sieve; and the active
component is one or more selected from the group consisting of
oxides and chlorides of alkali metals, alkali-earth metals, and
transition elements.
2. The catalyst for the preparation of dimethyl carbonate from urea
and methanol according to claim 1, characterized in that the alkali
metal is K, Na, Cs or Li.
3. The catalyst for the preparation of dimethyl carbonate from urea
and methanol according to claim 1, characterized in that the
alkali-earth metal is Ca or Mg.
4. The catalyst for the preparation of dimethyl carbonate from urea
and methanol according to claim 1, characterized in that the
transition element is Zn, Pb, Mn, La or Ce.
5. A method for preparing the catalyst for the preparation of
dimethyl carbonate from urea and methanol according to claim 1,
comprising the steps of: preparing an aqueous solution of soluble
metal salt(s) of alkali metal, alkali-earth metal, or transition
element according to the composition of the catalyst on weight base
of: active component: from 20 to 50 wt %, and carrier: from 80 to
50 wt %; adjusting pH value of the solution to 0-5; spraying and
impregnating the aqueous solution on a carrier by equal-volume
spraying and impregnating process, to prepare an active
component-supported carrier; drying the active component-supported
carrier at a temperature of from 100.degree. C. to 250.degree. C.
for 2 to 24 hrs; and finally calcining the dried active
component-supported carrier at a temperature of from 500.degree. C.
to 1000.degree. C. for 2 to 12 hrs.
6. The method according to claim 5, characterized in that the
soluble metal salt(s) is/are selected from the group consisting of
nitrates, acetates, oxalates, hydroxides and halides of alkali
metals, alkali-earth metals and transition elements.
7. The method according to claim 5, characterized in that the pH
value is in a range of from 1 to 3.
8. The method according to claim 5, characterized in that the
calcination temperature is in a range of from 650 to 850.degree.
C.
9. The method according to claim 5, characterized in that the
calcination time is in a range of from 3 to 8 hours.
10. A method for the preparation of dimethyl carbonate, comprising
the steps of: (1) dissolving urea in methanol to form a methanol
solution of urea, in which weight percentage of urea is in a range
of from 1% to 99%; (2) feeding the methanol solution of urea into a
catalyst bed layer from upper portion of catalyst section of a
catalytic rectification reactor in a feeding rate of from 0.01 to
10 ml/gcatmin, and feeding reaction raw material methanol into the
catalyst bed layer from lower portion of the catalyst section of
the catalytic rectification reactor in a feeding rate of from 0.01
to 20 ml/gcatmin, wherein reaction is carried out at conditions
including reaction temperature of from 120.degree. C. to
250.degree. C., reaction pressure of from 0.1 MPa to 5 MPa, kettle
bottom temperature of from 70.degree. C. to 210.degree. C.,
stripping section temperature of from 70.degree. C. to 250.degree.
C., rectifying section temperature of from 70.degree. C. to
280.degree. C., and reflux ratio of from 1:1 to 20:1, characterized
in that the catalyst used is as defined in claim 1.
11. The method according to claim 10, characterized in that the
weight percentage of urea in the methanol solution of urea is in a
range of from 20% to 50%.
12. The method according to claim 10, characterized in that the
feeding rate of the methanol solution of urea is in a range of from
0.1 to 2 ml/gcatmin.
13. The method according to claim 10, characterized in that the
feeding rate of the reaction raw material methanol is in a range of
from 0.1 to 10 ml/gcatmin.
14. The method according to claim 10, characterized in that the
reaction temperature is in a range of from 150.degree. C. to
200.degree. C.
15. The method according to claim 10, characterized in that the
reaction pressure is in a range of from 0.5 MPa to 3 MPa.
16. The method according to claim 10, characterized in that the
kettle bottom temperature is in a range of from 110.degree. C. to
180.degree. C.
17. The method according to claim 10, characterized in that the
stripping section temperature is in a range of from 150.degree. C.
to 190.degree. C.
18. The method according to claim 10, characterized in that the
rectifying section temperature is in a range of from 150.degree. C.
to 200.degree. C.
19. The method according to claim 10, characterized in that the
reflux ratio is in a range of from 1:1 to 6:1.
Description
TECHNICAL FIELD
[0001] The present invention relates to a catalyst and a method for
preparing the same, more particularly, to a supported catalyst for
direct synthesis of dimethyl carbonate from urea and methanol, to a
method for preparing the same, and to use thereof.
BACKGROUND ART
[0002] Dimethyl carbonate (DMC) is a novel "green" chemical product
to which great attention is paid both domestically and
internationally. Since DMC comprises methoxy group, carbonyl group
and carbonyl methyl oxygen group in a molecule, it exhibits high
reactivity, and could be used to replace for highly toxic phosgene
as carbonylating agent and for dimethyl sulfate as methylating
agent. DMC can be used as raw material to directly synthesize food
additives, anti-oxidants, plant protection agents, high performance
resins, fuels, pharmaceutical intermediates, surfactants, etc.,
thus it is praised as a potential "novel base block" in organic
synthesis. Furthermore, since DMC possesses relatively high oxygen
content as well as suitable vapor pressure, water resistance and
mixing distribution coefficient, it could serve as an ideal
gasoline additive. This further extension of the application of the
DMC will surely make DMC a new economic growing point in the
chemical industry, and is of practical significance due to huge
potential demands to DMC.
[0003] DMC was mainly synthesized by phosgene method in
conventional method. High toxicity of raw material phosgene and
corrosiveness of chlorine ion limited the large-scale production
and application of DMC. In 1983, Enichem Company in Italy developed
a non-phosgene method to synthesize DMC by oxidative carbonylation
of methanol in liquid phase [Romano U., Tesei R., Mauri M. M. et
al, Synthesis of dimethyl carbonate from methanol, carbon monoxide,
and oxygen catalyzed by copper compounds, Ind. Eng. Chem. Prod.
Res. Rev., 1980, 19: 396-403; Micheal A. P., Christopher L. M.,
Review of Dimethyl Carbonate (DMC): Manufacture and its
Characteristics as a Fuel Additive. Energy and Fuels 1997, 11,
2-29], which brought the synthesis of DMC to a new stage. In 1992,
UBE Industries Ltd. in Japan developed a method of gas-phase
oxidative carbonylation of methanol [J. Kizlink, Collect. Czech.
Chem. Comm. 1993, 58, 1399; Y. Sasaki, Chem. Lett., 1996, 825; S.
T. King, Reaction mechanism of oxidative carbonylation of methanol
to dimethyl carbonate in Cu--Y zeolite, J. Catal. 1996, 161,
530-538], and this made the synthesis of DMC quickly
commercialized. However, since the catalyst used in said method
comprises CuCl as main active component, the catalyst has strong
corrosion to facilities and short life, and the method suffers
expensive raw material gas and toxicity of CO. Another non-phosgene
method for preparing DMC is called transesterification method
[Knifton J. F., Duranleau R. G., Ethylene glycol-dimethyl carbonate
cogeneration, J. Mol. Catal., 1991, 67: 389-399; Nishihara K., U.S.
Pat. No. 5,292,917, 1993; Tatsumi T., Watanabe Y. and Koyano K. A.,
Synthesis of dimethyl carbonate from ethylene carbonate and
methanol using TS-1 as solid base catalyst., Chem. Commun.
1996(19): 2281-2282], wherein CO.sub.2 reacts with ethylene oxide
or propylene oxide in the presence of a catalyst to form ethylene
carbonate or propylene carbonate, and then ethylene carbonate or
propylene carbonate is subjected to transesterifying with methanol
to form DMC and ethylene glycol or propylene glycol. In comparison
with other synthetic methods, this process has the advantages of
cheaper raw materials, lower toxicity of raw materials, no three
wastes, high yield, and low corrosion, and the by-product, ethylene
glycol or propylene glycol, can be recovered. However, this method
has at present the disadvantages that the catalyst used has lower
activity and shorter life, reaction conditions are severe, and
organic solvents are used during the reaction so that the
subsequent separation of the products is difficulty and thus
facility investment as well as energy consumption is increased.
Therefore researching and developing new reaction approach to
further raise technological economical efficiency and technological
operability will be of importance.
[0004] In order to overcome the above-mentioned disadvantages, the
present inventors have developed a novel process and a novel
technique for the direct synthesis of DMC from urea and methanol,
as disclosed in Chinese Patent Application No. 01130478.2 entitled
"Method for preparation of dimethyl carbonate from urea and
methanol" and in Chinese Patent Application No. 01131680.2 entitled
"Method for preparation of dimethyl carbonate from urea and
methanol using heterogeneous catalyst". In such a method, since the
raw materials, urea and methanol, are common chemical raw
materials, their prices are rather low, and thus raw material cost
is lower. In addition, the method has other advantages such as safe
and simple process, higher activity of reaction and higher
selectivity of the product, and thus could significantly lower the
production cost of DMC. However DMC yield of said process is still
a little lower and needs further improvement.
DISCLOSURE OF THE INVENTION
[0005] The object of the invention is to provide a high conversion
and high selectivity supported catalyst for direct synthesis of DMC
from urea and methanol, a method for preparing the catalyst, and
use of the catalyst.
[0006] The catalyst of the present invention has a composition on
weight base as follows: [0007] active component: from 20 to 50 wt
%; and [0008] carrier: from 80 to 50 wt %.
[0009] Materials that could be used as the carrier include, but are
not limited to, active carbon, .alpha.-alumina, .gamma.-alumina,
silica, molecular sieve, and the like.
[0010] Active component is selected from the group consisting of
oxides and chlorides of alkali metals, alkali-earth metals and
transition elements, and mixture thereof.
[0011] The alkali metals include K, Na, Cs and Li.
[0012] The alkali-earth metals include Ca and Mg.
[0013] The transition elements include Zn, Pb, Mn, La and Ce.
[0014] The catalyst of the present invention can be prepared by a
method comprising the steps of: [0015] preparing an aqueous
solution of soluble salt(s) of alkali metal, alkali-earth metal, or
transition element according to the composition of the catalyst on
weight base; [0016] adjusting pH value of the solution to 0-5 by
KOH or NH.sub.3.H.sub.2O etc.; [0017] spraying and impregnating the
aqueous solution on a carrier by equal-volume spraying and
impregnating process, to prepare an active component-supported
carrier; [0018] drying the active component-supported carrier at a
temperature of from 100.degree. C. to 250.degree. C. for 2 to 24
hrs; and [0019] finally calcining the dried active
component-supported carrier at a temperature of from 500.degree. C.
to 1000.degree. C. for 2 to 12 hrs.
[0020] Useful soluble metal salts include nitrates, acetates,
oxalates, hydroxides, halides and the like of alkali metals,
alkali-earth metals, and transition elements.
[0021] The pH value is preferably adjusted to 1-3.
[0022] The calcination temperature is preferably in a range of from
650.degree. C. to 850.degree. C.
[0023] The calcination time is preferably in a range of from 3 to 8
hrs.
[0024] In the course of the preparation of the catalyst, control of
pH value of the aqueous solution, calcination temperature and
calcination time are the key points.
[0025] The catalytic reaction according to the present invention
can be carried out in a catalytic rectification reactor with the
catalyst loaded in the reaction section of the catalytic
rectification reactor. Methanol solution of urea formed by
dissolving urea in methanol enters the catalyst bed layer from the
upper portion of the catalyst section, with urea in the solution
entering the catalyst bed layer while methanol in the solution
entering the rectifying section of the catalytic rectification
reactor due to higher temperature. The reaction raw material
methanol enters catalyst bed layer from the lower portion of the
catalyst section. Urea and the reaction raw material methanol react
in the catalyst section to form DMC.
[0026] In a preferred embodiment, the catalyst according to the
invention is used in the catalytic rectification reactor in a
method comprising: [0027] (1) dissolving urea in methanol to form a
methanol solution of urea, in which weight percentage of urea is in
a range of from 1% to 99%; [0028] (2) feeding the methanol solution
of urea into the catalyst bed layer from upper portion of the
catalyst section of the catalytic rectification reactor in a
feeding rate of from 0.01 to 10 ml/gcatmin, and feeding reaction
raw material methanol into the catalyst bed layer from lower
portion of the catalyst section of the catalytic rectification
reactor in a feeding rate of from 0.01 to 20 ml/gcatmin, wherein
the reaction is carried out at conditions including reaction
temperature of from 120.degree. C. to 250.degree. C., reaction
pressure of from 0.1 MPa to 5 MPa, kettle bottom temperature of
from 70.degree. C. to 210.degree. C., stripping section temperature
of from 70.degree. C. to 250.degree. C., rectifying section
temperature of from 70.degree. C. to 280.degree. C., and reflux
ratio of from 1:1 to 20:1.
[0029] The weight percentage of urea in the methanol solution of
urea is preferably in a range of from 20% to 50%.
[0030] The feeding rate of the methanol solution of urea is
preferably in a range of from 0.1 to 2 ml/gcatmin.
[0031] The feeding rate of the reaction raw material methanol is
preferably in a range of from 0.1 to 10 ml/gcatmin.
[0032] The reaction temperature is preferably in a range of from
150.degree. C. to 200.degree. C.
[0033] The reaction pressure is preferably in a range of from 0.5
MPa to 3 MPa.
[0034] The kettle bottom temperature is preferably in a range of
from 1110.degree. C. to 180.degree. C.
[0035] The stripping section temperature is preferably in a range
of from 150.degree. C. to 190.degree. C.
[0036] The rectifying section temperature is preferably in a range
of from 150.degree. C. to 200.degree. C.
[0037] The reflux ratio is preferably in a range of from 1:1 to
6:1.
[0038] The present invention has the following advantages: [0039]
The catalyst according to the present invention is a supported
solid catalyst system, and the preparation of the catalyst is
simple and has good repeatability so that industrial scale
production can be easily achieved; reaction involving catalyst and
reactants is of multi-phase catalytic reaction, and thus there is
no need to separate catalyst from product; the novel supported
catalyst prepared could further enhance the yield of DMC in the
catalytic rectification reactor, and possesses higher reactivity
and selectivity; and by-product is less.
EMBODIMENTS
COMPARATIVE EXAMPLE
[0040] Using ZnO as Catalyst (catalyst was Obtained by Calcination
of ZnO)
[0041] 60.08 g of urea was dissolved in 602.7 g of methanol to form
a methanol solution of urea. Feeding rate of the methanol solution
of urea was 0.1 ml/gcat.min, and feeding rate of methanol was 0.5
ml/gcat.min. The reaction temperature was 200.degree. C., the
reaction pressure was 4.0 MPa, kettle bottom temperature was
170.degree. C., stripping section temperature was 200.degree. C.,
rectifying section temperature was 200.degree. C., and the reflux
ratio was 8:1. Results obtained were shown in Table 1.
EXAMPLE 1
[0042] 100 ml of 80 wt % aqueous solution of calcium nitrate was
prepared, and its pH value was adjusted to 1.5 by KOH. Said calcium
nitrate solution was sprayed and impregnated on 100 g of active
carbon carrier by equal-volume spraying and impregnating process,
and the carrier with active component supported thereon was then
dried at 150.degree. C. for 12 hrs and calcined at 700.degree. C.
for 6 hrs. The catalyst thus prepared had a composition of: calcium
oxide 21 wt %; and active carbon 79 wt %.
[0043] 60.08 g of urea was dissolved in 60.12 g of methanol to form
a methanol solution of urea. The methanol solution of urea was fed
into catalyst bed layer from upper portion of the catalyst section
of the catalytic rectification reactor in a feeding rate of 0.1
ml/gcat.min, and the reaction raw material methanol was fed into
the catalyst bed layer from the lower portion of the catalyst
section of the catalytic rectification reactor in a feeding rate of
0.5 ml/gcat.min. The reaction temperature was 150.degree. C., the
reaction pressure was 0.2 MPa, kettle bottom temperature was
80.degree. C., stripping section temperature was 85.degree. C.,
rectifying section temperature was 85.degree. C., and the reflux
ratio was 1:1. Results obtained were shown in Table 1.
EXAMPLE 2
[0044] 100 ml of 60 wt % aqueous solution of zinc acetate was
prepared, and its pH value was adjusted to 1.0 by KOH. Said zinc
acetate solution was sprayed and impregnated on 70 g of SiO.sub.2
carrier for 1 hr by equal-volume spraying and impregnating process,
and the carrier with active component supported thereon was then
dried at 250.degree. C. for 10 hrs and calcined at 500.degree. C.
for 12 hrs. The catalyst thus prepared had a composition of: zinc
oxide 24 wt %, and SiO.sub.2 76 wt
[0045] 60 g of urea was dissolved in 120.13 g of methanol. The
methanol solution of urea was fed into catalyst bed layer from
upper portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 1 ml/gcat.min, and the
reaction raw material methanol was fed into the catalyst bed layer
from the lower portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 5 ml/gcat.min. The
reaction temperature was 170.degree. C., the reaction pressure was
2.0 MPa, kettle bottom temperature was 130.degree. C., stripping
section temperature was 170.degree. C., rectifying section
temperature was 180.degree. C., and the reflux ratio was 2:1.
Results obtained were shown in Table 1.
EXAMPLE 3
[0046] 100 ml of 92 wt % aqueous solution of zinc acetate was
prepared, and its pH value was adjusted to 2.0 by KOH. Said zinc
acetate solution was sprayed and impregnated on 50 g of SiO.sub.2
carrier for 1 hr by equal-volume spraying and impregnating process,
and the carrier with active component supported thereon was then
dried at 150.degree. C. for 10 hrs and calcined at 800.degree. C.
for 12 hrs. The catalyst thus prepared had a composition of: zinc
oxide 41 wt %, and SiO.sub.2 59 wt
[0047] 60 g of urea was dissolved in 120.13 g of methanol. The
methanol solution of urea was fed into catalyst bed layer from
upper portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 1 ml/gcat.min, and the
reaction raw material methanol was fed into the catalyst bed layer
from the lower portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 2 ml/gcat.min. The
reaction temperature was 170.degree. C., the reaction pressure was
2.0 MPa, kettle bottom temperature was 130.degree. C., stripping
section temperature was 170.degree. C., rectifying section
temperature was 180.degree. C., and the reflux ratio was 2:1.
Results obtained were shown in Table 1.
EXAMPLE 4
[0048] 100 ml of 60 wt % aqueous solution of potassium nitrate was
prepared, and its pH value was adjusted to 1.2 by KOH. Said
potassium nitrate solution was sprayed and impregnated on 70 g of
SiO.sub.2 carrier for 1 hr by equal-volume spraying and
impregnating process, and the carrier with active component
supported thereon was then dried at 150.degree. C. for 10 hrs and
calcined at 800.degree. C. for 12 hrs. The catalyst thus prepared
had a composition of: potassium oxide 22 wt %, and SiO.sub.2 78 wt
%.
[0049] 60 g of urea was dissolved in 120.13 g of methanol. The
methanol solution of urea was fed into catalyst bed layer from
upper portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 1 ml/gcat.min, and the
reaction raw material methanol was fed into the catalyst bed layer
from the lower portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 5 ml/gcat.min. The
reaction temperature was 220.degree. C., the reaction pressure was
2.5 MPa, kettle bottom temperature was 180.degree. C., stripping
section temperature was 185.degree. C., rectifying section
temperature was 220.degree. C., and the reflux ratio was 2:1.
Results obtained were shown in Table 1.
EXAMPLE 5
[0050] 100 ml of 40 wt % aqueous solution of cesium nitrate was
prepared, and its pH value was adjusted to 3.5 by KOH. Said cesium
nitrate solution was sprayed and impregnated on 70 g of SiO.sub.2
carrier for 1 hr by equal-volume spraying and impregnating process,
and the carrier with active component supported thereon was then
dried at 180.degree. C. for 10 hrs and calcined at 800.degree. C.
for 12 hrs. The catalyst thus prepared had a composition of: cesium
oxide 25 wt %, and SiO.sub.2 75 wt %.
[0051] 30 g of urea was dissolved in 120.13 g of methanol. The
methanol solution of urea was fed into catalyst bed layer from
upper portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 1 ml/gcat.min, and the
reaction raw material methanol was fed into the catalyst bed layer
from the lower portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 5 ml/gcat.min. The
reaction temperature was 190.degree. C., the reaction pressure was
2.0 MPa, kettle bottom temperature was 130.degree. C., stripping
section temperature was 180.degree. C., rectifying section
temperature was 190.degree. C., and the reflux ratio was 4:1.
Results obtained were shown in Table 1.
EXAMPLE 6
[0052] 100 ml of an aqueous solution containing 2 wt % of potassium
oxalate and 85 wt % of zinc nitrate was prepared, and its pH value
was adjusted to 2.0 by KOH. Said solution was sprayed and
impregnated on 50 g of .gamma.-alumina carrier for 2 hrs by
equal-volume spraying and impregnating process, and the carrier
with active component supported thereon was then dried at
100.degree. C. for 15 hrs and calcined at 750.degree. C. for 4 hrs.
The catalyst thus prepared had a composition of: potassium oxide 5
wt %, zinc oxide 40 wt %, and alumina 55 wt %.
[0053] 60.08 g of urea was dissolved in 320.7 g of methanol. The
methanol solution of urea was fed into catalyst bed layer from
upper portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 3.5 ml/gcat.min, and the
reaction raw material methanol was fed into the catalyst bed layer
from the lower portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 9 ml/gcat.min. The
reaction temperature was 180.degree. C., the reaction pressure was
2.0 MPa, kettle bottom temperature was 180.degree. C., stripping
section temperature was 180.degree. C., rectifying section
temperature was 180.degree. C., and the reflux ratio was 4:1.
Results obtained were shown in Table 1.
EXAMPLE 7
[0054] 50 ml of 2 wt % potassium nitrate aqueous solution and 50 ml
of 80 wt % zinc nitrate aqueous solution were prepared, and their
pH values were adjusted to 2.0 by KOH. Said solutions were sprayed
and impregnated on .gamma.-alumina carrier for 1 hr by equal-volume
spraying and impregnating process, respectively, and the carrier
with active component supported thereon was then dried at
150.degree. C. for 8 hrs and calcined at 800.degree. C. for 8 hrs.
The catalyst thus prepared had a composition of: potassium oxide 2
wt %, zinc oxide 31 wt %, and Al.sub.2O.sub.3 67 wt %.
[0055] 60.08 g of urea was dissolved in 60.7 g of methanol. The
methanol solution of urea was fed into catalyst bed layer from
upper portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 0.5 ml/gcat.min, and the
reaction raw material methanol was fed into the catalyst bed layer
from the lower portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 1.5 ml/gcat.min. The
reaction temperature was 200.degree. C., the reaction pressure was
2.0 MPa, kettle bottom temperature was 170.degree. C., stripping
section temperature was 200.degree. C., rectifying section
temperature was 200.degree. C., and the reflux ratio was 8:1.
Results obtained were shown in Table 1.
EXAMPLE 8
[0056] 25 ml of 5 wt % potassium nitrate aqueous solution was
prepared and its pH value was adjusted to 4.0 by KOH, while 75 ml
of 80 wt % calcium nitrate aqueous solution was prepared and its pH
value was adjusted to 2.0. Said solutions were sprayed and
impregnated on .alpha.-alumina carrier for 2 hrs by equal-volume
spraying and impregnating process, respectively, and the carrier
with active component supported thereon was then dried at
170.degree. C. for 10 hrs and calcined at 700.degree. C. for 6 hrs.
The catalyst thus prepared had a composition of: potassium oxide 2
wt %, zinc oxide 35 wt %, and Al.sub.2O.sub.3 63 wt %.
[0057] 60.08 g of urea was dissolved in 20.07 g of methanol. The
methanol solution of urea was fed into catalyst bed layer from
upper portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 2 ml/gcat.min, and the
reaction raw material methanol was fed into the catalyst bed layer
from the lower portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 5 ml/gcat.min. The
reaction temperature was 200.degree. C., the reaction pressure was
4.0 MPa, kettle bottom temperature was 170.degree. C., stripping
section temperature was 200.degree. C., rectifying section
temperature was 200.degree. C., and the reflux ratio was 8:1.
Results obtained were shown in Table 1.
EXAMPLE 9
[0058] 25 ml of 5 wt % cesium nitrate aqueous solution was prepared
and its pH value was adjusted to 5.0 by KOH, while 75 ml of 60 wt %
calcium nitrate aqueous solution was prepared and its pH value was
adjusted to 2.0. Said solutions were sprayed and impregnated on 50
g of .alpha.-alumina carrier for 2 hrs by equal-volume spraying and
impregnating process, respectively, and the carrier with active
component supported thereon was then dried at 170.degree. C. for 10
hrs and calcined at 650.degree. C. for 6 hrs. The catalyst thus
prepared had a composition of: cesium oxide 3 wt %, calcium oxide
22 wt %, and Al.sub.2O.sub.3 75 wt %.
[0059] 60.08 g of urea was dissolved in 72.7 g of methanol. The
methanol solution of urea was fed into catalyst bed layer from
upper portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 1.0 ml/gcat.min, and the
reaction raw material methanol was fed into the catalyst bed layer
from the lower portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 4.0 ml/gcat.min. The
reaction temperature was 200.degree. C., the reaction pressure was
1.0 MPa, kettle bottom temperature was 170.degree. C., stripping
section temperature was 200.degree. C., rectifying section
temperature was 200.degree. C., and the reflux ratio was 8:1.
Results obtained were shown in Table 1.
EXAMPLE 10
[0060] 5 ml of 35 wt % lanthanum nitrate aqueous solution was
prepared and its pH value was adjusted to 4.0 by KOH, while 95 ml
of 70 wt % zinc nitrate aqueous solution was prepared and its pH
value was adjusted to 2.0 by KOH or NH3.H2O. Said solutions were
sprayed and impregnated on 70 g of active carbon carrier for 1 hr
by equal-volume spraying and impregnating process, respectively,
and the carrier with active component supported thereon was then
dried at 150.degree. C. for 8 hrs and calcined at 700.degree. C.
for 3 hrs. The catalyst thus prepared had a composition of:
lanthanum oxide 2 wt %, zinc oxide 28 wt %, and active carbon 70 wt
%.
[0061] 174.96 g of urea was dissolved in 29.7 g of methanol. The
methanol solution of urea was fed into catalyst bed layer from
upper portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 2 ml/gcat.min, and the
reaction raw material methanol was fed into the catalyst bed layer
from the lower portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 5 ml/gcat.min. The
reaction temperature was 200.degree. C., the reaction pressure was
1.5 MPa, kettle bottom temperature was 200.degree. C., stripping
section temperature was 200.degree. C., rectifying section
temperature was 200.degree. C., and the reflux ratio was 10:1.
Results obtained were shown in Table 1.
EXAMPLE 11
[0062] 100 ml of 70 wt % magnesium hydroxide aqueous solution was
prepared, and its pH value was adjusted to 1.5 by KOH. Said
solution was sprayed and impregnated on 70 g of molecular sieve
carrier for 1 hr by equal-volume spraying and impregnating process,
and the carrier with active component supported thereon was then
dried at 150.degree. C. for 8 hrs and calcined at 650.degree. C.
for 3 hrs. The catalyst thus prepared had a composition of:
magnesium oxide 30 wt %, and molecular sieve 70 wt %.
[0063] 74.96 g of urea was dissolved in 459.7 g of methanol to form
a solution. The methanol solution of urea was fed into catalyst bed
layer from upper portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 1 ml/gcat.min, and the
reaction raw material methanol was fed into the catalyst bed layer
from the lower portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 3 ml/gcat.min. The
reaction temperature was 200.degree. C., the reaction pressure was
2.0 MPa, kettle bottom temperature was 200.degree. C., stripping
section temperature was 200.degree. C., rectifying section
temperature was 200.degree. C., and the reflux ratio was 4:1.
Results obtained were shown in Table 1.
EXAMPLE 12
[0064] 10 ml of 20 wt % aqueous solution of potassium nitrate was
prepared and its pH value was adjusted to 3.0 by KOH. 10 ml of 35
wt % aqueous solution of lanthanum nitrate and 80 ml of 80 wt %
aqueous solution of zinc nitrate were prepared and their pH value
were adjusted to 2.0. Said solutions were sprayed and impregnated
on 70 g of .gamma.-alumina carrier for 1 hr by equal-volume
spraying and impregnating process, and the carrier with active
component supported thereon was then dried at 150.degree. C. for 8
hrs and calcined at 700.degree. C. for 3 hrs. The catalyst thus
prepared had a composition of: potassium oxide 2 wt %, lanthanum
oxide 2 wt %, zinc oxide 27 wt %, and Al.sub.2O.sub.3 69 wt %.
[0065] 74.96 g of urea was dissolved in 459.7 g of methanol to form
a solution. The methanol solution of urea was fed into catalyst bed
layer from upper portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 10 ml/gcat.min, and the
reaction raw material methanol was fed into the catalyst bed layer
from the lower portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 20 ml/gcat.min. The
reaction temperature was 200.degree. C., the reaction pressure was
1.5 MPa, kettle bottom temperature was 200.degree. C., stripping
section temperature was 200.degree. C., rectifying section
temperature was 200.degree. C., and the reflux ratio was 10:1.
Results obtained were shown in Table 1.
EXAMPLE 13
[0066] 100 ml of 70 wt % magnesium chloride aqueous solution was
prepared and its pH value was adjusted to 1.5 by KOH. Said solution
was sprayed and impregnated on 60 g of molecular sieve carrier for
1 hr by equal-volume spraying and impregnating process, and the
carrier with active component supported thereon was then dried at
150.degree. C. for 8 hrs and calcined at 950.degree. C. for 2 hrs.
The catalyst thus prepared had a composition of: magnesium chloride
50 wt %, and molecular sieve 50 wt %.
[0067] 74.96 g of urea was dissolved in 459.7 g of methanol to form
a solution. The methanol solution of urea was fed into catalyst bed
layer from upper portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 1 ml/gcat.min, and the
reaction raw material methanol was fed into the catalyst bed layer
from the lower portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 3 ml/gcat.min. The
reaction temperature was 200.degree. C., the reaction pressure was
2.0 MPa, kettle bottom temperature was 200.degree. C., stripping
section temperature was 200.degree. C., rectifying section
temperature was 200.degree. C., and the reflux ratio was 4:1.
Results obtained were shown in Table 1.
EXAMPLE 14
[0068] 100 ml of 70 wt % lead nitrate aqueous solution was prepared
and its pH value was adjusted to 0.5 by KOH. Said solution was
sprayed and impregnated on 60 g of molecular sieve carrier for 1 hr
by equal-volume spraying and impregnating process, and the carrier
with active component supported thereon was then dried at
150.degree. C. for 10 hrs and calcined at 750.degree. C. for 10
hrs. The catalyst thus prepared had a composition of: lead oxide 36
wt %, and molecular sieve 64 wt %.
[0069] 74.96 g of urea was dissolved in 459.7 g of methanol to form
a solution. The methanol solution of urea was fed into catalyst bed
layer from upper portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 0.2 ml/gcat.min, and the
reaction raw material methanol was fed into the catalyst bed layer
from the lower portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 0.8 ml/gcat.min. The
reaction temperature was 185.degree. C., the reaction pressure was
1.0 MPa, kettle bottom temperature was 120.degree. C., stripping
section temperature was 170.degree. C., rectifying section
temperature was 185.degree. C., and the reflux ratio was 4:1.
Results obtained were shown in Table 1.
EXAMPLE 15
[0070] 100 ml of 60 wt % sodium nitrate aqueous solution was
prepared and its pH value was adjusted to 3.5 by KOH. Said solution
was sprayed and impregnated on 70 g of silica carrier for 1 hr by
equal-volume spraying and impregnating process, and the carrier
with active component supported thereon was then dried at
180.degree. C. for 10 hrs and calcined at 800.degree. C. for 12
hrs. The catalyst thus prepared had a composition of: sodium oxide
25 wt %, and SiO.sub.2 75 wt %.
[0071] 30 g of urea was dissolved in 120.13 g of methanol to form a
solution. The methanol solution of urea was fed into catalyst bed
layer from upper portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 1 ml/gcat.min, and the
reaction raw material methanol was fed into the catalyst bed layer
from the lower portion of the catalyst section of the catalytic
rectification reactor in a feeding rate of 5 ml/gcat.min. The
reaction temperature was 190.degree. C., the reaction pressure was
2.0 MPa, kettle bottom temperature was 130.degree. C., stripping
section temperature was 180.degree. C., rectifying section
temperature was 190.degree. C., and the reflux ratio was 4:1.
Results obtained were shown in Table 1. TABLE-US-00001 TABLE 1
Results of the reaction Conversion of urea % DMC yield % ve Example
96.89 49.73 Example 1 98.50 58.91 Example 2 97.62 53.56 Example 3
99.66 68.56 Example 4 97.24 58.12 Example 5 98.75 59.42 Example 6
100.00 62.98 Example 7 100.00 76.88 Example 8 100.00 74.92 Example
9 99.12 64.75 Example 10 98.54 75.68 Example 11 98.54 55.65 Example
12 98.98 70.29 Example 13 98.12 52.48 Example 14 99.89 62.68
Example 15 98.18 52.35
* * * * *